Heater for fluids



April 11, 1944. Q A L I 2,346,345

HEATER FOR FLUIDS Filed Feb. 20, 1942 #BlZPNERS BURNEPS Y\ o O 0 82 9 2010 O Q0 0 o B 20 o 20 o 2/ O Q g o O O O 0 g o o 0 O O O facing the tubebanks in the side Patented Apr. 11, 1944 HEATER FOR FLUIDS Charles H.Angeli, Chicago, 111., assignor to Universal Oil Products Company,Chicago, 113., a

corporation of Delaware Application February 20, 1942, Serial No.431,703 Claims. (01. 122-356) This invention relates to an improved formof heater for fluids which is particularly advantageous as applied toheating hydrocarbons to the high temperatures required for their thermalor catalytic conversion. It to heating other fluids and will be usefulwhenever it is desired to heat one or more streams of the same ordifferent fluid under substantially the same or under different heatingconditions and with relatively high rates of heat input.

The heater provided is of the type employing a plurality of separatelyflred cells or radiant heat ing zones in which flames and hot combustiongases from the firing means are passed vertically over the surface ofthereby heated 'to a highly radiant condition, radiant heat beingtransmitted directly from said wall and from the flames and hotcombustion gases passing thereover to the tubular elements of the fluidconduit disposed within said cell.

In one specific embodiment of the invention the heater comprisesexterior refractory side and end walls, a floor and a roof andvertically disposed interior refractory walls extending between the endwalls and from the floor to an elevation somewhat beneath the roof.These interior walls are spaced from each other to provide a centrallydisposed cell or combustion and radiant heating zone therebetween and avertically disposed bank of tubes is located substantially midwaybetween the interior walls in said central cell, The interior walls arealso spaced fromthe side walls to provide another cell or combustion andradiant heating zone between each interior wall and the adjacent sidewall. A vertically disposed bank of tubular fluid conduits is located ineach of the last mentioned cells adjacent the surface of the interiorwall and a fluid heatirig zone containing a bank of tubular fluidconduits is disposed beneath and in direct communication with each ofthe last named cells. A row of burners is disposed adjacent the base ofeach of walls for projecting flames and hot combustion gases upwardlythrough the central cell over and in intimate contact with the surfaceof themterior walls facing said centrally disposed tube bank. A row ofburners is disposed adjacent the top of each of said side walls forprojecting flames and hot combustion gases downwardly over and inintimate contact with the surfaces of the latter cells. Compass over theside cells and bustlon gases from the central cell top of said interiorwalls into the thence downwardly therethrough and combustion gases fromeach of the side cells are directed is, however, well adapted arefractory wall which isthe interior 4 through the communicating fluidheating zone and thence from the heater through flues communicating withthe stack.

Various modifications of the specific form of heater, above described,are within the scope of the invention, as willbe subsequently explained.

The accompanying diagrammatic drawing represents a sectional end view ofone specific form of the heater provided by the invention and itsfeatures and advantages will be more apparent with reference to thefollowing description of the drawing.

The heater hereillustrated tially vertical refractory side walls I and2, a refractory roof 3, a floor 4, end walls (not shown) and foundationwalls 5, 6, 1 and 8.

Substantially vertical comprises substanspaced from each other Acentrally disposed flred' cell or combustion and radiant heating zone II is provided between walls 9 and In. Another independently fired cellor adJacent the floor 4 to adjacent the upper exsubstantially verticalrow of horizontally disposed is located in zone 42 adjacent the surfaceof wall 9. Another tube bank 23, also comprising, in this instance, asingle substantially vertical row of horizontally disposed tubes 24, islocated in zone 43 adjacent the surface of wall it. Another tube bank25, comprising a plurality of superimposed horizontal rows ofhorizontally disposed tubes 23, is located in fluid heating zone It anda similar bank 21 comprising a plurality of superimposed horizontal rowsor horizontally disposed tubes 23, is located in, fluid heating zone IS.

A row of bumers, one of which is indicated at 29, is disposed withinburner compartment i8 adjacent the base of wall 9 and another tow ofburners, also designated by the reference numeral 29, is disposed inzone l8 adjacent the base of wall l0. Firing ports 30 are provided infloor I for the burners 29 and flames and hot coinbustion gases aredirected upwardly from the burners and burner ports over and in intimatecontact with the surfaces of walls 9 and i through zone I. These wallsare thereby heated to a highly radiant condition and radiant heat istransmitted directly from the walls and from the flames and hotcombustion gases passing thereover to the tubes of bank IS. The tubes ineach row of bank I! are staggered with respect to the tubes in the otherrow thereof so that each tube receives radiant heat on one side fromwall 9 and from the flames and hot combustion gases passing thereoverand on its opposite side from zone ill and the flames and hot combustiongases passing thereover.

Combustion gases which have given up a substantial portion of theirradiant heat to the tubes of bank I9 pass from zone between the upperends of walls 9 and I0 and the roof 3 into zones i2 and I3. Preferably,to maintain substantially stream-line flow, and to assist insubstantially equally dividing the combustion gases tions to which eachof the tube banks l9, 2| and- 23 is subjected, are controlledindependently of the heating conditions for the other tube banks of thisgroup and that banks 2| and 23 may be subjected to substantiallyidentical or to different heating conditions. Also, the heatingconditions about tube bank 25 are controlled independently of thoseabout tube bank 21. This construction and arrangement makes the heaterexceptionally flexible with respect to contro1 of the heating curve forthe fluid undergoing treatment and,

from zone Ii between zones i2 and I3 and direct said gases toward thesurfaces of walls I and 2, the interior surface of roof 3 is curved, asillustrated in the drawing, with a bull-nose 3| projecting downwardlyinto the space immediately above zone II and tube bank l8.

The combustion gases from zone H which are directed into zone |2 passdownwardly therethrough in contact with the interior surface of wall Iand their volume and temperature is increased to the desired degree asthey enter zone H by the addition thereto of fresh flames and hotcombustion gases directed downwardly through zone |2 over the surface ofwall I from a row of burners, one of which is indicated at 32, disposedadjacent the upper end of wall I, firing ports 33 being provided forthese burners in roof 3.

In the same manner, combustion gases supplied, as previously described,from zone H to zone I3, pass downwardly through the latter over thesurface of wall 2 and their volume and temperature is increased to thedesired degree as they enter zone I3 by the addition thereto of freshflames and hot combustion gases supplied through burner ports 33 fromthe row of burners 32 disposed adjacent the upper end of wall 2.

In passing through zones l2 and I3 the combustion gases from zone H andthe fresh flames and hot combustion gases from burners 32 heat theinterior surfaces of walls I and 2 to a highly radiant condition andheat is supplied from these walls and from the flames and hot combustiongases passing downwardly thereover to one side of each of the tubes ofthe respective banks 2| and 23. The opposite side of each of the tubesof bank 2| is heated by reflected radiation from the adjacent surface ofwall 9 and the opposite side of each of the tubes of bank 23 is heatedby reflected radiation from adjacent wall in.

The combustion gases which have given up a in addition to permittingheating of a single stream of fluid in banks i9, 2| and 23, with greaterflexibility of the heating curve employed, it permits the heating of twoor more separate streams of the same fluid or of different fluids undersubstantially the same or under different heating conditions for eachstream.

The invention is not limited to any particular sequence of flow throughthe various tube banks, but permits a wide variety of specific hook-upswhich may be selected to suit requirements and correlated with theheating conditions employed in the various cells to give the resultsdesired. However, the following examples are given to illustrate a fewof the many possible specific flows which may be advantageouslyemployed.

to the lower row of bank 25 and passes in series through the adjacenttubes in each row and through the several rows in a generally upwarddirection, being transferred from the uppermost row of bank 25 to thelower end of bank 2| and passing through the adjacent tubes of this bankin series in a general upward direction, to be discharged from theuppermost tube of bank 2|. Simultaneously, a separate stream ofdifferent fluid is passed in substantially the same manner through banks21 and 23 and a third stream of another fluid is passed serially throughthe tubes of bank l9. By independent control of the heating conditionsin zones l2 and i3, each of the three streams may be subjected todifferent heating conditions. 1

Example [I ployed for zones l2 and I3 so that each of the two streams isheated under substantially identical conditions in the respective banks2| and 23 and in the respective banks 25 and 21. By

substantially equal firing of zone H on opposite sides ofbank l9, eachofthe streamsis also subjected to substantially identical heatingconditions in the opposite rows of this bank. This type of flowis-particularly advantageous when it is desired to employ differentheating conditlons' for initial-treatment of the fluid as it passesthrough the heating coil, as compared with'those employed at a laterperiod in its heat treatment. For example, hydrocarbon distillate to bereformed, such as gasoline or gasoline fractions of low antiknock value,naphtha or the like, may, with this flow, be quickly heated to thedesired'high cracking temperature at the outlet of coils 2| and 23 andthen passed through tube bank lswhich comprises a soaking sectionwherein the fluid is maintained at or near the maximum temperaturepreviously attained for a predetermined time to complete the desiredreforming operation.

Example -III As a modificationof the flow given in Example II, above,thetwo streams from banks 21 and 23,

- instead of passing through opposite rows of bank l8, maybe commingledin one of the end tubes of this bank and passed serially through theadjacent tubes in opposite rows of bank I 9 in either a general upwardor a general downward direction.

Example I V.

In anothermodification of the flow given in Example 11, the sequentialarrangement of banks is, 2| and 23'maybe reversed, a stream'of fluidfrom bank 25 being-directed throughthe left hand row of bank 19 andthence through bank 2|, while a stream of fluid from'bank' 2]is'directed through the right-hand row of bank; l9 and thence throughbank 23.

By employing different heating conditions in zones l2 and I3, the flowgiven in Example II'or the fiow givenin Example IV maynbeadvantageouslyemployed inheating two streams. of different fluid under difierentheating conditions and to difierentoutlet temperatures, particularlywhen relatively mild heating conditions, as com- "pared with thoseemployed in zones l2 and 13,

are utilizedin zone II, or vice versa, or when different heatingconditions are employed on opposite sides of bank IS in zone ll.

Various modifications of the specific formofheater illustrated and abovedescribed will be apparentto those familiar with the artand are entirelywithin the scope of the invention. For example, bank I9 may comprise asingle row or more than two substantially parallel rows of tubes'insteadof the two-row arrangement illustrated. Also, two or moresubstantiallyparallel rows of tubes may be employed for bank 2| or forbank'23, or both, instead of the single row illustrated. The adjacenttubes in each row of the individual banks may be connected in series attheir ends and adjacent rows may be connected in parallel or-in series.Alternatively, the tubes in each row or in various sections of each rowmay be connected for the parallel flow of separate streams of fluidtherethrough and it is also within the scope of the invention to em ploysubstantially vertically disposed tubes in any or all of the variousbanks l9, 2! and 23,

instead of the. horizontally disposed tubes.- It is also within thescope of the invention to invert the heater, firing cell II, in adownward direction'and cells I2 and I3 in an upward'direction.

One of the outstanding features and advantages of the invention residesin the provision for directing combustion gases from the central cellof-the heater-through the side cells wherein they supply a substantialportion of their residual heat to the respective banks 2! and 23'andwherein their volume and temperature is'increased to the desireddegree by firing of the burners individual to cells i2 and 13. Thispermits good utilization of the residual radiant heat in-thecombustiongases from zone H and is particularly advantageous when more severeheating conditions are employed about bank l5 than those about bank 2!and 23. The invention is, however, not limited to firing zone l2 and Bfrom burners 32 and,

when desired, one of the zones H or B may be the heater here shown.

Iclaim as my invention: 1. A heater for fluids comprising, incombination, a radiant heating zone disposed between a pair ofsubstantially vertical refractory walls, a

substantially vertical bank of tubular fluid conduits disposed in saidzone substantially midway between said walls, another radiant heatingzone adjoining the first named zone and disposed between'a pair ofsubstantially vertical refractory walls, a substantially vertical bankof tubular fluid conduits disposed in said other heating zone adjacentthe surface of'onlygine of said refractory walls thereof, means fordirecting hot combustion gases through the first named zone over said'walls thereof in direct radiant heat transmlttlng relation to the tubebank dis sed therein, means for directing hot combustion'gases throughthe second named zone over the surface of that'wall thereofopposite thetube bank disposed therein and in direct radiant heat transmittingrelation to said'tube'bank, and means for directing combustion gasesfrom one of said zones into and through the other of said zones.

2. A heater for fluids comprising, in combination, a radiant heatingzone disposed between a pair of substantially vertical refractory walls,a substantially vertical bank of tubular fluid'conduits disposed in saidzone substantially midway between said walls,another radiant heatingzone adjoiningthe first namedzone and disposed between a pair ofsubstantially vertical refractory walls, a substantially vertical bankof tubular fluid conduits disposed in said other heating zone adjacentthe surface of only one of said refractory wallsthereof, means fordirecting hot combustion gases through the first named zone over saidWalls thereof in a substantially vertical direction and indirect radiantheat transmitting relation to the tube bank disposed'therein, means fordirecting hot combustion gases through the second named zone over thesurface of that wall thereof.

tion, a radiant heating zone disposed between a pair of substantiallyvertical refractory walls, a

4- asaasas substantially vertical bank of tubular fluid conthe firstnamed tube bank, means for directing duits disposedin said zonesubstantially midway between said walls. another radiant heating zoneadjoining the flrst named zone and disposed between a pair ofsubstantially vertical refractory walls, asubstantially vertical bank oftubular fluid conduitsdisposed in said other heating zone adjacent thesurface of only one of said refractory walls thereof, means fordirecting hot combustion -'gases through the first namedzone over saidwalls thereof in a substantially vertical'direction and in directradiant heat transmitting relation to the tube bank disposed therein,means for directing hot combustion gases through the second named zoneover the surface of that wall thereof opposite the tube bank disposedtherein in, a substantially vertical direction reverse to that employedin the first named'zone and in direct 'radiant heat transmittingrelation to said tube bank, and means for directing combustion gasesfrom one of said zones into and through the other of said zones.

4. A heater such as defined in claim 1, provided with means, comprisingburners disposed adjacent. one end of each of the walls over which saidhot combustion gases are passed, for generating flames and hotcombustion gases in each of said zones. 1

5. Aheater for fluids comprising, in combination, a radiant heating zonedisposed between a.

pair of substantially vertical refractorywalls, a

substantially vertical bank of tubular fluid con.-

gases through the first named zone over the surface of saidwallsthe'reof in a substantially vertical direction and in directradiant heat transmitting relation to the tube bank disposed therein,means for directing hot combustion gases through each of said otherzones over the surface of that wall thereof opposite the 'tubebankdisposed therein, and means for directing cornbustion gases from thefirst named zone into and.

through said other zones. l

6. A heater for fluids comprising-in combination, a radiant heating zonedisposed between a pair of substantially vertical refractory walls, asubstantially vertical bank of tubular fluid conduits disposed in saidzone substantially midway between saidwalls, other radiant heatingzonesadjoining and disposed on opposite sides of the first named zone, eachof said other zones being disposed between one of'said walls of thefirst named zone and-on opposite substantially vertical refractory wall,a substantially vertical bank of tubular fluid conduits disposed,adjacent the surface of one of said walls in each -of said other heatingzones, means, comprising burners ,dis-

posed adjacent one endcf each of said walls of the first named zone,for'gene'rating flames and hot combustion gases in the flrst'named zoneand for directing the same vertically over said walls in direct radiantheat transmitting relation to flames and hotcombustion gases upwardlyinto. the firstnamed zone over the surface of said in-- combustion gasesfrom theend of the first'named zone opposite said burners into each ofsaid other zones, means comprising burnersmdividual to each of saidother zones for generating flames-and hotcombustion gases .therein tocommingle with said combustion gases from the first 'nam'edzone and fordirecting the commingled gases'vertically over 'the surface of that wallin each of said other zones opposite the tube bank disposed therein andin. direct radiant heat transmitting relation tosaid tubebank.

'7. Aheater such as defined in claim 5-,- having a fluid heating zoneindividual to andv communieating with each of the second named radiantheating zones, 9. bank of tubular fluid conduitsin each .of saidfluidheating zones, and means for directingcombustion gases from each ofthe sec.- ond named radiantheating zones through the communicating fluidheating zone in contact with said tube bank disposed therein.

8. A heater such as defined in claim 6, having afluid heating zoneindividual to and communieating with each of the second named radiantheating zones, a bank of tubular fluid conduits in each of said fluidheating zones, and means for directing combustion gases from each of thesecond named radiant heating zones through the communicating fluidheating zone in contact with said tube bank disposed therein.

9. A heater for fluids comprising, in combination, refractory sidewalls, end walls, a floor and a roof, interior walls spaced from eachother and extending from saidfloor to an elevation beneath said roof toprovide a radiant heating zone therebetween, said interior walls alsobeing spaced from..said.side walls to; provide.a separate radiantheating zone between each interior wall and the adjacent side wall, asubstantially vertical bank of tubular fluid conduits disposed in thefirst named radiant heating zone substantially midway between saidinterior walls, a bank of tubular fluid conduits disposed in each ofsaid separate radiant heating zones adjacent said interior wall thereof,burners disposedadjacent the.

base of each of said interior walls for directing terior walls facingthe first namedtube-bank, burners disposed adjacent the upper end ofeach of said side walls for directing flames and hot combustion gasesdownwardly through each of said separate radiant heating zones over thesurfaces'of said side walls which face the second named tube banks,means for directing combustion gases from the first named zone overtheupper ends of said interior walls into each of said separate zones andmeans for removing combustion gases from the lower end of each of saidseparate radiant heating zones. 1103A" heater such as defined inclaim-9, having a fluid heating zoneindividual to and commnnicating witheach of said separate radiant heating zones, a bank of tubular fluidconduits in each of said fluid heating zones, and means for directing"combustion gases from each of said separate radiant heating zonesthrough the com.-

municating fluid heating zone in contact with said tube bank disposedtherein.

- CHARLES H. ANGELL.

